What does vortexing do in transformation? - (Dec/07/2011 )

What would vortexing competent cells do during the transformation process (i.e. thawing from -80, after adding plasmid DNA etc)?

Will it lyse the cells?

Competent cells are fragile, so yes I think that vortexing them will kill a great deal of them. When I add my DNA prior to transformation, I mix gently with a large bore pipette, or invert several times, then incubate the cells on ice for about 15-30 min.